How it works

KINOLT KS® System Description

The KINOLT KS® is such a simple piece of equipment that one might think of it as a conventional generator-set. It is made up of a diesel engine that is coupled to a kinetic energy accumulator, via an electromagnetic clutch. The kinetic energy accumulator is the combination of a Kinetic energy accumulator and a synchronous machine.

The KINOLT KS® also includes a control panel and a choke/power panel.

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How does it work?

In the heart of the KINOLT KS®‚ is its kinetic energy accumulator; a clever but simple system to store and retrieve kinetic energy. The kinetic energy accumulator consists of two rotating parts: the outer rotor runs mechanically-free around the inner rotor. The inner rotor, driven by the main shaft, rotates at 1500 rpm (50 Hz) or 1800 rpm (60 Hz). It contains two sets of windings; a three-phase AC winding and a DC winding.

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Energy storage

In conditioning mode, the AC winding is powered to generate a rotating magnetic field which turns the outer rotor to the speed of maximum 3000 rpm. However, the relative speed between inner and outer ring of the bearings is only 1500 rpm, since the shaft itself is rotating at 1500 rpm. The outer rotor stores kinetic energy advantageously, since the amount of kinetic energy increases quadratically with the distance from the centre of rotation.

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Energy retrieval

In independent mode, the DC winding is powered and the outer rotor is electrically coupled to the inner rotor by induction. Its kinetic energy is transferred to the inner rotor - it drives it. This energy transfer is regulated by accurately controlling the current injected into the DC winding. The kinetic energy accumulator is a totally brushless system.

Operation description

Conditioning Mode

In conditioning mode, when the mains supply is within tolerance, the synchronous machine is acting as a motor, driving the main shaft and thus the accumulator, storing kinetic energy in it. When the inner rotor rotates at 1500 rpm (50 Hz) or 1800 rpm (60 Hz), the outer rotor then rotates at maximum 3000 rpm. The kinetic energy is thus stored

Independent mode

During mains failure or voltage perturbation the stored kinetic energy is now transferred to the kinetic energy accumulator, which acts as a generator. This happens without any interruption to the user.

Shortly after, the diesel engine starts and couples to the kinetic energy accumulator by latching the electromagnetic clutch. The energy is then relayed from the diesel engine to the synchronous machine and then to the loads.

Sequence:

  • QD1 opens
  • The kinetic energy transferred from the outer rotor maintains the frequency at 50 Hz (or 60 Hz) within +/- 1%
  • The engine starts
  • The electromagnetic clutch closes

When the engine reaches 1500rpm (1800 rpm for 60 Hz), it transfers power to the load, until the mains supply returns.

Transfer From Conditioning Mode To Independent Mode

This concerns the transfer from conditioning to independent mode and back. The frequency is maintained within narrow tolerances, the accumulator’s speed decreases and then the diesel engine starts to provide power to the load.

In the event of a diesel engine start-up failure, the electromechanical clutch will close shortly after opening QD1 and the kinetic energy of the accumulator will start the diesel engine. This gives the KINOLT KS® a redundant start possibility; a second guarantee to start the engine.

Mains Return Back To Conditioning Mode

  • The KINOLT KS®‚ synchronises with the mains supply.
  • The outer rotor is re-accelerated to its rated speed.
  • When the rated kinetic energy is stored, QD1 closes.
  • The electromagnetic clutch opens.
  • The diesel engine runs at idle speed for cooling and then stops eventually.
  • The system secures the critical load against an unlimited number of repeated mains failures.